Although various Power Line Communication (PLC) systems have been introduced over the years, no scheme has proven reliable and inexpensive enough to become widespread. Difficulties present in the powerline environment, including noise, severe resonances, complex topologies, large attenuation, and time-varying parameters, have prevented several schemes from achieving reliable communication. Recent advances in technology, include inexpensive microcontroller and digital signal processors, have improved modern PLC schemes' chances of success. However, PLC success is still not assured, and as a result, a need for PLC-specific test equipment exists. Without such test equipment, it would be difficult or impossible for a PLC system to be successfully planned, deployed, and maintained.
There are two fundamental classes of PLC protocols, specifically control protocols and broadband protocols (referred to as Broadband over Power Lines, or BPL). Control protocols are typically low-bandwidth, less complicated, and used mainly for device control and automation, such as lighting control or other similar applications. Control protocols include, but are not limited to, X-10, INSTEON, KNX, UPB, LonWorks, and CEBus. These protocols are generally below 500 kHz, but can be at any suitable frequency. BPL protocols are high bit-rate, broadband, typically in the range of 1-30 MHz, but can be at any suitable frequency. BPL protocols include, but are not limited to, HomePlug (1.0, Turbo, and AV), HD-PLC, and OPERA. These protocols can be used for high-speed LAN activity such as internet access, streaming A/V content or any other suitable application. Modulation schemes are complex, and are generally based on orthogonal frequency-division multiplexing (OFDM). The two PLC classes were not designed to work together, but are often present in the same powerline network, and can interfere with each other.